#include <iostream>

namespace my_space {
    int a = 10;
    int b = 20;
    int my_add(int left, int right) {
        return left + right;
    }
    int my_sub(int left, int right) {
        return left - right;
    }
}

// using namespace my_space;
using my_space::my_add;

int main() {
    std::cout << my_space::a << std::endl;
    // std::cout << b << std::endl;
    int s = my_add(11, 15);
    std::cout << s << std::endl;
}

